Carrier PC 111 Operating And Troubleshooting Manual

Also see for 48FK034: Controls operation and troubleshooting

2CONTENTS (cont)PageTROUBLESHOOTING. . . . . . . . . . . . . . . . . . . . . . . . . 44-60Checking Display Codes . . . . . . . . . . . . . . . . . . . . . . . . 44Complete Unit Stoppage . . . . . . . . . . . . . . . . . . . . . . . . 44Single Circuit Stoppage . . . . . . . . . . . . . . . . . . . . . . . . . 44Restart Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45Diagnostic Codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45• CODES 51, 52, 55, 56: COMPRESSOR FAILURE• CODES 59 AND 60: LOW-PRESSURE SWITCH• CODES 63 AND 64: OIL PRESSURE SWITCH• CODE 70: ILLEGAL UNIT CONFIGURATION• CODES 71 TO 76: THERMISTOR/RESISTORFAILURE• CODE 81: RESET THERMISTOR ORPOTENTIOMETER FAILURE• CODE 82: SUPPLY-AIR TEMPERATURE SET POINTPOTENTIOMETER FAILURE• CODE 83: ECONOMIZER FEEDBACKPOTENTIOMETER FAILURE• CODE 84: RESET LIMIT POTENTIOMETERFAILURE• CODE 85: DEMAND LIMIT POTENTIOMETER (P4)FAILURE• CODE 86: MINIMUM POSITION ECONOMIZERPOTENTIOMETER FAILURE• CODE 87: WARM-UP TEMPERATURE SET POINTFAILUREThermistor Troubleshooting. . . . . . . . . . . . . . . . . . . . . 48Electronic Controls Checkout . . . . . . . . . . . . . . . . . . . 48• PROCESSOR BOARD CHECKOUT• RELAY BOARD TROUBLESHOOTING• DISPLAY BOARD CHECKOUT• ACCESSORY BOARD CHECKOUT• TWO-STEP DEMAND LIMIT CONTROL MODULE(DLCM) TROUBLESHOOTINGEnthalpy Sensor Checkout . . . . . . . . . . . . . . . . . . . . . . 52Economizer Motor. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52Supply Fan Variable Frequency Drive . . . . . . . . . . . 52• STANDARD TRANSDUCER CONTROL• EXTERNAL SIGNAL CONTROL• SUPPLY FAN MOTOR OVERLOAD PROTECTION• VFD OPERATION• VFD OPERATIONAL STATUS• RESTORING FACTORY VFD DEFAULTSPower Exhaust Variable Frequency Drive . . . . . . . 55• STANDARD TRANSDUCER CONTROL• EXTERNAL SIGNAL CONTROL• POWER EXHAUST FAN MOTOR NO. 1 OVERLOADPROTECTION• POWER EXHAUST VFD OPERATION• POWER EXHAUST VFD OPERATIONAL STATUS• RESTORING FACTORY POWER EXHUAST VFDDEFAULTSUnit Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57START-UP CHECKLIST. . . . . . . . . . . . . . . . . . CL-1, CL-2SAFETY CONSIDERATIONSInstalling, starting up, and servicing this equipment can behazardous due to system pressures, electrical components, andequipment location (roof, elevated structures, etc.). Onlytrained, qualified installers and service mechanics should in-stall, start up, and service this equipment.When working on this equipment, observe precautions inthe literature; on tags, stickers, and labels attached to the equip-ment, and any other safety precautions that apply. Follow allsafety codes. Wear safety glasses and work gloves. Use care inhandling, rigging, and setting this equipment, and in handlingall electrical components.GENERALCarrier 48FK,FM,JK and 50FK,FM,FS,FY,JK,JY units pro-vide ventilation, cooling, and heating (when equipped) in Vari-able Air Volume (VAV) applications. These units contain facto-ry-installed controls which provide full system management.The unit controls also perform self diagnostic tests at unit start-up, monitor operation of the unit, and provide alarms. Informa-tion on system operation and status are sent to the central pro-cessors by various sensors that are located at the unit and in theconditioned space. Each unit is equipped with a display board.Rooftop Information — The rooftop controls cyclesupply-fan motor, compressors, and unloaders to maintain theproper temperature conditions. The controls also cycle con-denser fans to maintain suitable head pressure. Safeties arecontinuously monitored to prevent the unit from operating un-der abnormal conditions. The controls provide control of econ-omizer and cycle or control heating as required.The controls also allow the service person to operate a‘quick test’ so that all the controlled components can bechecked for proper operation.VAV Control System — The 30 to 100-ton VAV roof-top units contain a microprocessor-based electronic controlsystem that controls and monitors the rooftop unit functions.The VAV control system is composed of several components:• processor board• relay board• display board• thermistors• compressor operation feedback (control relay)• accessory board• temperature reset package*• single-step demand limit*• two-step demand limit control module**Field-installed accessories.Electrical shock can cause personal injury and death. Shutoff all power to this equipment during installation and ser-vice. There may be more than one disconnect switch. Tagall disconnect locations to alert others not to restore poweruntil work is completed.This unit uses a microprocessor-based electronic controlsystem. Do not use jumpers or other tools to short out com-ponents, or to bypass or otherwise depart from recom-mended procedures. Any short-to-ground of the controlboard or accompanying wiring may destroy the electronicmodules or electrical components.IMPORTANT: This literature contains controls, opera-tion, and troubleshooting data for 48FK,FM,JK and50FK,FM,FS,FY,JK,JY variable air volume rooftopunits. Use this guide in conjunction with the separateInstallation Instructions literature packaged with theunit.IMPORTANT: The field-supplied and installed switch(or timeclock) MUST BE CLOSED to put unit into theOccupied mode. Unit WILL NOT START until this isaccomplished. See base unit installation instructions lit-erature for details.